6. Biological War

Image Credit

With conventional wars it’s a matter of two or more rivals hurling bombs and bullets at each other until one is defeated and then life goes back to normal. That may not be the case with a war that involves the use of biological agents or germ warfare. Once you turn a lethal virus or other deadly germ lose on your enemies, it’s not so easy to put it back in the bottle. It’s conceivable that a deadly pathogen used for warfare could spread around the world and virtually wipe out all human life.